1. Field of the Invention
The present invention relates to a diagnostic imaging apparatus, a magnetic resonance imaging apparatus, and an X-ray Computed Tomography (CT) apparatus each of which performs a scan by setting scanning conditions so as to collect data synchronously with a cardiac waveform of a subject. The present invention particularly relates to a technology for determining timing of little cardiac motion automatically without additional special scan or operator's determination.
2. Description of the Related Art
Conventionally, among methods of a cardiac scan performed by a magnetic resonance imaging apparatus, particularly a scan that requires a high spatial resolution, for example, coronary angiography, there has been a method of selectively collecting data in a time phase of little cardiac beat within a cardiac cycle for suppressing degradation in image quality due to cardiac motion (for example, see Stuber M, et al. “Submillimeter Three-dimensional Coronary MR Angiography with Real-Time Navigator Correction: Comparison of Navigator Locations”, Radiology 1999; 212: 579-587). According to the method, a scan is performed by setting a predetermined delay time and a predetermined data-collection period (window), and it is known that such delay time and a period of little cardiac beat depend on beats per minute of a patient.
To ensure image quality of a cardiac scan, particularly coronary angiography, a method of performing a scan is proposed such that, for example, a cine scan for a short time adequate to recognize motion of a subject artery is preliminarily performed, an operator visually determines a period of little cardiac beat, and then the scan is performed by setting such period with respect to each patient (for example, see Plein S, et al. “Three-Dimensional Coronary MR Angiography Performed with Subject-Specific Cardiac Acquisition Window and Motion-adopted Respiratory Gating.” AJR 2003; 180: 505-512).
However, according to the conventional methods described above, apart from a series of examinations, an additional cine scan of a cross section on which a coronary artery is to be visualized needs to be performed by newly performing positioning, and furthermore, the operator needs to set timing of a scan visually. For this reason, according to the conventional methods, an examination time may be sometimes extended, so that burdens to an operator and a patient are increased; and image quality may be unstable in some cases due to variations in scan timing performed by an operator.